TL;DR
An S-trap is an obsolete drain configuration in which the trap's outlet turns down and continues vertically through the floor, forming an S shape that modern plumbing codes prohibit in new work because the falling slug of water can siphon the trap dry and let sewer gas into the room. The compliant P-trap instead exits horizontally to a vented wall arm that breaks the siphon.
What it means
An S-trap is an obsolete drain configuration in which the trap's outlet turns down and continues vertically through the floor, forming an S shape that modern plumbing codes prohibit in new work because the falling slug of water can siphon the trap dry and let sewer gas into the room. The compliant P-trap instead exits horizontally to a vented wall arm that breaks the siphon. Inspectors flag these under older sinks routinely, and an air admittance valve plus re-piping is the usual cure.
Where it sits in the glossary
S-trap is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
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